1. Field of the Invention
The field of the invention is generally rotary drilling apparatus which utilizes fluid such as compressed air, water or other agents for cooling the bit and for other purposes and especially to the provision of some means located between the end of the drill pipe and the fluid passages in the rotary bit for the purpose of dividing and directing the air to provide a more efficient utilization thereof.
2. Description of Prior Apparatus & Methods
A conventional rotary drill string comprises the sections of drill pipe and a conventional rotary drill bit on the end thereof. It is well known to introduce fluids such as compressed air or other agents through the pipe and down the inside of the drill string to assist in drilling the hole by cooling the bit, assisting and keeping the bearings and the rollers of the bit clean and blowing (bailing) rock chips out of the hole. The relationship of the compressed air and the removal of the rock chips becomes critical in the life of a drill bit. If the velocity of the air is too fast as the air passes through the bit then a condition exists in which very small particles of rock are picked up by the fast moving air and impact against the bit causing premature wear. This condition is called sandblasting. If the velocity of the air is too slow as it passes through the bit there occurs a condition called regrinding during which the air is not moving fast enough to blow the large rock chips away from the bit and to the top of the hole. The rock chips are then crushed again and again by the bit as it rotates causing a very abrasive condition of very small particles of rock around the bit creating excessive heat by the bombardment of small bodies. Such action causes premature wear on the bit. Perhaps the single item that does the most damage to a drill bit is the rock chips that the bit cuts from the bottom of a hole. The least expensive way to remove the chips from around the bit is to blow them away with compressed air. However, as mentioned above, previously the lack of proper direction and control of the air has caused sandblasting and regrinding and excessive heat.
While there have been efforts in the prior art to control and direct the compressed air or other fluids and mixtures it has not been through the use of the apparatus of the present invention or in the method which is performed by the use of the present apparatus.
With reference to the above discussion, the following U.S. patents are noted: Nos.
2,898,086 PA1 2,951,680 PA1 3,094,175 PA1 3,095,052 PA1 3,848,683 PA1 3,899,033